Limitations: Subgroups not identified, adherence hard to assess
The uncertainty of any benefit of treatment with bisphosphonates beyond 5 years is further reflected in U.S. recommendations – the Food and Drug Administration has concluded on the basis of pooled data from the extension phase of major clinical trials that any advantages of treatment beyond 3-5 years are unclear.
Key limitations of the current study include the fact that the incidence of hip fracture was not evaluated in low-risk vs. high-risk subgroups; therefore, “these findings may not be applicable to older women at higher risk of osteoporotic fracture,” the authors wrote.
Furthermore, the study did not assess outcomes of fractures other than hip fractures, such as vertebral fractures, they noted.
Dr. Adler pointed out that another limitation is that adherence in the trial was defined as taking 60% of prescribed pills.
“I think this is the biggest weakness with the study,” he said. “Particularly with medications like oral bisphosphonates that don’t really make patients feel any different, it’s a real challenge to make sure patients continue to take these drugs properly.”
The findings should give some reassurance for patients who take a break from the drugs after 5 years. However, reassessment of their risk is critical, Dr. Adler reiterated.
The study was supported by a grant from the National Institute on Aging and the National Institute of Arthritis, Musculoskeletal, and Skin Diseases of the National Institutes of Health. The authors and Adler have disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.